the race is on to find life in other places in the solar system from
underground reservoirs on Mars to the subsurface oceans on Europa and
Enceladus if spacecraft Rovers or even astronauts
make the momentous discovery of life on another world that'll just open up new
questions did it originate all on its own completely independently from Earth
or are we somehow related and if we are related how long ago did our
evolutionary trees branch away from each other even though Mars is millions of
kilometres away it could be possible that we're still related thanks to the
concept of panspermia the idea that meteor impacts could transfer rocks and
maybe even living creatures from world to world but could you go one step
further if we find life on another star system could we discover that we're
actually related to them - is galactic pence per meeow possible before I get
talking about pence per Mia on a galactic level I'd first like to just
bring everyone up to speed on regular old panspermia the concept was
popularized by Fred Hoyle Chandra Wickramasinghe and John Watkins in the
1986 book called viruses from space and related matters they discovered that
dust in space contained organic compounds and proposed that new diseases
could be falling to earth from space this would explain why disease outbreaks
seem to happen randomly around the world but planetary scientists have known for
a while that larger objects do travel from world to world meteorites the Allen
hills 84001 meteorite discovered as part of a survey in Antarctica was found to
contain captured gases that match the atmosphere of ancient Mars at some point
about 17 million years ago a meteor struck Mars and debris was thrown off
into space faster than Mars's escape velocity some of this material orbited
into the inner solar system in alh for 0:01 enter the Earth's atmosphere about
11,000 years ago getting scooped up in 1984
by meteorite hunters in fact this has happened a lot there are more than 70
Martian meteorites in the hands of scientists the surprising discovery is
how well various life-forms can withstand the extreme conditions of
space and then spring back to life when they're returned to earth-like or even
Mars like conditions in an experiment from 2014 to 2016 samples of various
earth life-forms from fungi to cyanobacteria were exposed to the vacuum
extreme temperatures and ultraviolet radiation of space itself outside the
International Space Station after they were brought back to earth and return to
more reasonable conditions they were able to recover to continue on even in a
simulated mars-like environment it's still not clear if organisms can survive
for long periods of time orbiting around the Sun in the harsh vacuum of space but
life has already shown us what it's capable of as they say in that dinosaur
movie life finds a way when samples are returned from Mars or a serious life
finding robotic laboratory travels to Mars or if SpaceX delivers human
scientists to Mars and if they do find life that just sets off a cascade of new
questions is it life as we understand it with DNA RNA and similar processes to
life on Earth if it is are we related and if we are when did we branch off it
could be possible to figure out roughly when a meteorite from Mars landed on
earth never get me wrong if we do find life on Mars or Europa it'll be one of
the most important scientific discoveries in human history but if it
turns out that we're all related that doesn't tell us anything about whether
there's life anywhere else in the universe what about getting life from
star to star will we eventually discover that all life in the universe is related
now I know that Star Trek proposed this idea in the next generation that various
humanoid species were related across the galaxy but that's science fiction
humanity clearly evolved right here on earth one of the weird things about life
on Earth is the fact that it's been around for so long
the earth is 4.5 billion years old and there's direct evidence of bacterial
colonies that lived almost 3.5 billion years ago and if you calculate a common
ancestor life probably arose from hydrothermal vents in the oceans as far
back as 3.8 billion years ago and some researchers suggest that it's even older
literally as old as the earth itself which seems kind of unusual
it's amazing that life arose the moment that it could so what if it was seeded
from another star system and took hold as soon as conditions were acceptable
you would think that one mechanism to get life across the galaxy would be to
just scale up planetary meteorite impacts but instead of getting just
enough escape velocity to get away from Mars or earth an object could be shot
fast enough to escape the entire solar system but that's a big jump in velocity
while the escape velocity of Mars is 5.03 km/s you need 9.4 km/s to just get
into low-earth orbit and to go from Earth orbit to escaping the entire solar
system requires another 42.1 km/s the voyagers pioneers and new horizons were
able to achieve this feat by doing gravity assists past the massive planets
in the solar system the problem is that planets like Earth which are big enough
to generate a protective magnetosphere are too difficult to escape from another
idea is that light pressure and the solar winds could push lighter material
out into the galaxy but anything outside the protective magnetosphere of a place
like Earth experiences relentless ultraviolet radiation inside the solar
system and then damage from cosmic rays in interstellar space this radiation
strikes the DNA molecules of life essentially killing it although even if
material was long dead when it reached a more hospitable environment it could
still be a source of complex organic molecules and give life a kickstart in
another world the term for this idea is necro panspermia
in theory life could be protected inside rocky objects as small as one meter
across but these would be too difficult to push with light pressure alone neat
objects smaller than a millimeter to escape the pull of the Sun of course one
last idea is that life is being intentionally seeded from world to world
by aliens and this is known as directed panspermia but come on once you say
aliens did it the argument is pretty much over
aliens could have done anything or nothing we've talked about how difficult
it would be for meteorite impacts to send debris out into the galaxy but
there might be another way comets and we'll talk about that in a
second but first I'd like to thank Sebastian - Berg Daniel Lee Frank and
the rest of our 842 patrons for their generous support educational content
should be freely available to anyone in the world and the patrons make this
possible join our community at patreon.com slash universe today and get
in on the action Aamir Suraj and avi Loeb recently wrote a paper called
exporting terrestrial life out of the solar system with gravitational
slingshots of earth grazing bodies and while I guess the title really explains
it all there they looked into whether it could be possible for asteroids or
comets skimming through the Earth's atmosphere to carry biological material
out into the galaxy life on Earth is mostly on the ground and in the oceans
but some of it is also in the atmosphere in fact microorganisms have been
discovered at altitudes as high as seventy seven kilometres this is high
enough that a long-period comet from the Oort cloud could just graze the Earth's
atmosphere scoop up a face full of bacteria and then fly out into deep
space again and if that comet encounters a planet or large objects in the Kuiper
belt it could be kicked out into an
interplanetary trajectory that takes it from the solar system out to another
star thanks Jill mwah and comment - I Borissov we know that comets can get
kicked out of their star systems and make an interstellar journey in fact
there could be thousands of objects in the solar system right now Siraj and
Loubs simulated what might happen if a long-period comet passes through the
Earth's atmosphere these objects are key because they just barely hold
in orbit around the Sun and it doesn't take much to kick them into an
interstellar trajectory they calculated how much atmospheric drag the objects
would receive as they pass through the atmosphere and also how much of a
gravity slingshot they get and they also determined how many bacteria would get
scooped up by comet as passed through the atmosphere incredibly bacteria can
easily handle the kinds of instantaneous acceleration you'd get slamming into a
comet screaming through the atmosphere hundreds of thousands or even millions
of G's of force and based on their calculations they estimated that this
event could have happened up to 100,000 times in history of the earth and we
haven't had a bright comet visible in the Northern Hemisphere's night sky
since hatake back in 1996 and that was 15 million kilometers away imagine
seeing a comet pass right through the Earth's atmosphere live long enough and
you might see that happen it's gotta wait 45,000 years or so and if life has
ever found floating as high as 100 kilometers in the Earth's atmosphere
Siraj and Loeb think that it would dramatically increase the number of
escapees think of the trillions of planets across the Milky Way in the
comets carrying living material on an escape velocity out of all those star
systems and it makes you wonder if all life in the galaxy might be related of
course if there is life across the Milky Way we don't see any evidence of
advanced civilizations out there so yeah we're back to the Fermi paradox but then
maybe it still means that only earth ever evolved multicellular organisms
single cellular life might be everywhere but only earth has animals and
intelligence of course so much of this is going to remain purely theoretical
for a very long time even if we could sample interstellar comets a tiny
fraction of them would contain any interstellar bacteria and if we do
perceive faint bio signatures in the next generation of monster telescopes we
can't actually perceive their DNA yet the only way to know once and for all is
to send a mission to another star and actually sample them too
correctly and of course if we do we'll send our bacteria with us what do you
think let me know your thoughts in the comments here are the names of the
patrons who support us at the $10 level and more want to see your name here and
support the work we do go to patreon.com/scishow Universe Today
once a week I gather up all my space news into a single email newsletter and
send it out it's got pictures brief highlights about the story and links you
can find out more go to Universe Today that calms ash newsletter to sign up and
did you know that all of my videos are also available in a handy audio a
podcast format so you can have the latest episodes as well as special bonus
material like interviews with me show up right on your audio device go to
Universe Today the Commish audio or search for Universe Today on iTunes
Spotify or wherever get your podcasts and I'll put a link in the show notes
observing another world and even knowing if there's life there is going to be a
difficult task we did a whole video about the concept of bio signatures and
how difficult it's going to be to know once and for all if there's
extraterrestrial life watch that next